This invention relates generally to the field of antennas. More specifically, a dual position antenna is provided that is particularly well-suited for use with a radio transceivers such as radio modems.
Communication devices having radio transceivers are known. Many types of antenna structures are also known, including helix, xe2x80x9cinverted Fxe2x80x9d, and retractable antenna structures, for example. Helix and retractable antennas are typically installed outside of a mobile device, and inverted F antennas are typically embedded inside a case or housing of a device. In general, helix antennas and embedded antennas such as inverted F antennas have a single operating mode. Although an internal antenna may operate when a device in which the internal antenna is installed is oriented in different directions, the operating mode of the antenna itself does not change. Similarly, retractable antennas are typically optimized to operate when the antenna is in an extended position.
In some circumstances, such as in PCMCIA radio modems, for example, internal space limitations preclude the use of high-performance embedded antennas. However, fixed external antennas for such devices are often inconvenient when a device must be stored or handled. Retractable antennas improve storage and handling, but known designs are more intrusive when in use, requiring antennas to be extended for operation.
A dual mode antenna system for a wireless transceiver is provided. The antenna system comprises a retractable antenna element having a retracted position and an extended position, and a loading structure. The antenna element is connected to the loading structure in the retracted position and operates in a first operating mode, and is disconnected from the loading structure and operates in a second operating mode in the extended position.
According to another embodiment of the invention, an antenna system comprises a dual position antenna having a first position and a second position, wherein the dual position antenna operates as a first type of antenna in the first position and as a second type of antenna in the second position.
In a still further embodiment, an antenna system comprises a top load and a retractable antenna element. The retractable antenna element has a retracted position and an extended position. In the retracted position, the retractable antenna element is connected to the top load to form a low-profile antenna. In the extended position, the antenna element forms a monopole antenna.
Further features of dual mode antenna systems will be described or will become apparent in the course of the following detailed description.